Hi csilverdds,
Besides the suggestions and information in the previous link … the best suggestion I can make is to follow the steps in post #1 here once you have decided on the types of materials and components that are acceptable to you.
If you are looking at memory foam I would make sure at a minimum that they met the guidelines in post #10 here (if you choose to go with memory foam at all) and with latex I would make sure that it was certified by Oeko-Tex or a similar test for offgassing and harmful substances although it would not be common to find latex that had an issue with this.
Phoenix